The present invention relates generally to hydraulically powered differential steered agricultural machines, and more particularly to an improved assembly for controlling hydraulic pump swashplate angles in such machines.
Hydrostatic drive systems are often configured with the drive pump attached directly to the engine without a clutch or other mechanism to stop output flow of the pump while the engine is running. Drive pump displacement (output) and therefore speed in differential-steered machines is controlled by variations in swashplate angle which is adjusted by movement of external pintel arms external to the pumps. On most pumps, pintel arm and thus swashplate rotation from “neutral” to “full speed” occurs over a relatively narrow range on the order of 16-18 degrees. With such a small range of motion, it is important that the assembly controlling the angular position of the pintel arm angles be capable of precise angular control. Precise control of the swashplate angle for hydrostatic ground drive pumps on differential-steered agricultural machines is paramount, especially when operating the machine at higher travel speed such as is necessary for road transport between fields. Without precision control, relative movement between the control assembly and the swashplate can lead to unintended changes in swashplate angle, perceived by the operator as loose steering or changes in ground speed.
It would be of great advantage to provide an improved swashplate control assembly mounting that minimizes distance and thus potential for relative motion between the control assembly and the swashplate pintel arms. Additional advantages would be realized by an improved mounting system that is easily incorporated into the existing swashplate control design commonly used on current model hydrostatic drive differential-steered machines.